Hydraulic spring adjusting device for bowl mills

ABSTRACT

A pulverizing mill having a grinding roller which is biased towards a grinding ring by means of a compression spring assembly. A portable spring adjusting jig can be temporarily attached to the spring assembly to quickly and easily test or adjust the compression of the spring.

United States Patent 1 1 1111 3,881,348

Morton May 6, 1975 [541 HYDRAULIC SPRING ADJUSTING DEVICE 3,531,937 10/1970 Johnson 73/161 FOR BOWL MILLS 3,638,486 2/1972 Lambert 73/161 John Allison Morton, Helena, Ala.

Combustion Engineering, Inc., Windsor, Conn.

Filed: June 20, 1973 Appl. No.: 371,638

Inventor:

Assignee:

Int. Cl. G011 l/02 Field of Search 241/121; 92/117; 72/243; 73/161, 191 R I References Cited UNITED STATES PATENTS l/i960 Droke 73/161 US. Cl 73/141 R; 73/161; 241/121 Primary ExaminerRoy Lake Assistant ExaminerE. F. Desmond Attorney, Agent, or Firm-Robert L. Olson [57] ABSTRACT A pulverizing mill having a grinding roller which is biased towards a grinding ring by means of a compression spring assembly. A portable spring adjusting jig can be temporarily attached to the spring assembly to quickly and easily test or adjust the compression of the spring.

3 Claims, 2 Drawing Figures A I// Wm PATENTEDMAY 61975 SHEET 2 OF 2 A w //////M/ HYDRAULIC SPRING ADJUSTING DEVICE FOR BOWL MILLS BACKGROUND OF THE INVENTION Many present pulverizing mills utilize a rotating bowl having a race or grinding ring upon which a number of rollers rotate, to thus pulverize or comminute coal or other material it is desired to grind to a given fineness. The rollers are biased towards the ring by means of compression spring assemblies. In order to insure consistency of fineness over periods of usage, the compression of the spring assemblies must be tested, to make sure their compression remains constant. Over long periods of usage, spring characteristics may change somewhat. Also, if different materials are to be pulverized in the same mill, it may be desirable to change the compression of the spring assemblies. Because of the large size of present pulverizing mills and grinding rollers, spring assemblies exerting forces within the range of 30,000-60,000 psi are common. These required large forces pose problems in testing or adjusting the compression of the spring assemblies. The present recommended means of adjustment of the roller journal spring compression is by dismounting the entire spring assembly from the pulverizer and transferring it to a shop for spring adjustment. In a plant having six pulverizers with three rollers each, this procedure is cumbersome and time-consuming.

SUMMARY OF THE INVENTION This invention is directed to a portable compression spring adjusting jig that can be easily attached and detached from spring assemblies in-place. The jig includes an hydraulic jack for determining and setting the compressive force of the spring assembly.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. I is a sectional side view of a pulverizing mill; and

FIG. 2 is an enlarged sectional view of the portable spring adjusting apparatus of the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT Looking now to FIG. 1, numeral designates a bowl mill for grinding coal or other material therein. Inside the housing is positioned a rotatable bowl or ring 12, mounted on shaft 14. Shaft 14 along with the attached bowl is rotated by means of worm wheel 18, which engages worm 16 mounted on a motor driven shaft.

One or more grinding elements or rollers 20 are rotatably mounted on shafts 22. Adjustable spring 24 urges the roller 20 towards the inner surface of the grinding ring 12, by exerting a force on arm 23. The roller 20 is pivotally mounted on shaft 25.

Coal to be pulverized is introduced into the mill through inlet 36. Air enters through opening 26, and flows through annular space 32 to convey the ground material passing over the lip upwardly through the mill interior and into the classifier 30. The air and coal enter the classifier through inlets 28. The larger particles of insufficiently ground coal fall back onto the grinding surface through bottom opening 34 for further grinding, and the finer particles are carried along by the air and are discharged through outlets 38.

Looking now to FIG. 2, apparatus for testing or adjusting the compression of the spring 24 is shown. The

spring assembly itself comprises a spring 24, one end of which is seated on spring seat 40, which is also in contact with roller arm 23. The other end of spring 24 is seated against plate 42. Stud or rod 43 is threadably or otherwise suitably connected to seat 40. The spring 24 is housed within housing 44. A nut 46 is threaded onto the outer end of rod 43, and is in contact with the outer surface of 42. The longitudinal position of nut 46 with respect to rod 43 determines the amount of compression in spring 24.

The spring adjusting apparatus comprises a nut 50 which can be threaded onto the outer end of rod 43. A second rod 52, threaded at both ends, is threaded into the outer end of nut 50. surrounding the rod 52 is a jig 48, having an inner ring base 47 for resting against the outer surface of plate 42. A plurality of legs or rods 51 are integral with inner base ring 47, and an outer base ring 49. The open spaces 53 between legs 51 permits ready access of nut 46 during the spring adjustment operation. An annular hydraulic jack 54 is located outwardly longitudinally along rod 52. A spacer member 56, and a retainer nut 58 complete the assembly along rod 52. A hydraulic pump 60 is connected to the jack 54, and a pressure gauge 62 is connected to the pressure line.

The manner in which the compression in a spring assembly is tested or adjusted will now be described. If there is a cover for plate 42 or nut 46 (not shown), this is first removed. Also, if there is a lock nut on top of nut 46 (not shown), this is removed. The mounting nut 50 is then threaded onto the end of rod or stud 43, and the second rod 52 is threaded into nut 50. The compression jig is then slipped over rod 52, so that its base 47 rests on the outer surface of plate 42. Next, the jack 54 and spacer 56 are slipped over the end of rod 52 and positioned. Retainer nut 58 is then threaded onto the end of stud 52.

By using pump 60, pressure in jack 54 can be increased, causing opening of the jack parts, and movement of plate 42, and thus a slight compression of spring 24. The gauge 62 registers the hydraulic pressure built up in the jack 54. If desired, a second chart can be placed on the gauge, so that a direct conversion of hydraulic pressure to spring force is made. For example, for every 1,000 pounds hydraulic pressure registered with use of a given jack, the spring force may be 15,000 psi. Thus 30,000 psi spring force would be equivalent to 2,000 pounds hydraulic pressure.

When the compression in spring 24 has been tested or properly adjusted, the operator reaches in through opening 53 and threads the nut 46 downwardly until it snugly contacts the outer surface of plate 42. The hydraulic pressure can then be released from the jack 54 in any suitable manner (not shown). The retainer nut 58 is then removed, allowing disassembly and removal of the entire spring adjusting apparatus, and the operator can move on to another spring assembly.

From the above, it can be seen that a single operator can easily and quickly check or adjust the compression of spring assemblies in-place in a pulverizing mill through the use of the portable hydraulic spring adjusting apparatus.

What is claimed is:

1. Means for adjusting the compression of a spring including a rod, coupling means at a first end of the rod adapted to be connected to a center stud of a spring, jig means surrounding the rod, said jig means having a space inside thereof.

2. The combination set forth in claim 1, wherein the means for causing opening of the jack is a source of fluid, and means for varying the pressure of the fluid.

3. The combination set forth in claim 2, wherein the means for determining the force exerted by the jack is a pressure gauge for measuring the pressure of the fluid. 

1. Means for adjusting the compression of a spring including a rod, coupling means at a first end of the rod adapted to be connected to a center stud of a spring, jig means surrounding the rod, said jig means having a first base at one end adapted to come in contact with a spring seat, said jig means having a second base at its other end, an annular fluid jack surrounding the rod and being in contact at one end with the second base, means for causing opening of the jack, retaining means secured to a second end of the rod for maintaining the jack in contact with the jig, means for determining the force exerted by the jack, the jig means having an opening in the side wall thereof to permit accessibility to the space inside thereof.
 2. The combination set forth in claim 1, wherein the means for causing opening of the jack is a source of fluid, and means for vaRying the pressure of the fluid.
 3. The combination set forth in claim 2, wherein the means for determining the force exerted by the jack is a pressure gauge for measuring the pressure of the fluid. 